Novel X-ray tomography technique enables faster, non-destructive 3D imaging of nanoscale details of objects

X-ray computed tomography is a cost-effective imaging tool frequently used in materials science to provide three-dimensional structural information of objects in a non-destructive way. In microelectronics packaging, the electrical behavior of metallic interconnects directly depends on their structural integrity – defects at the nanoscale may lead to negative effects on device performance such as resistance variations and voltage reduction, thus the development of new materials calls for technologies able to efficiently access nanoscale 3D information. Recently, researchers from France, U.S. and Netherlands have made key improvements in a Scanning Electron Microscopy (SEM) based X-ray tomography technique to provide such 3D information, which they report in Review of Scientific Instruments in 2017.

In SEM-based equipment, X-rays are generated through the interaction between a highly-focused electron beam and a geometrically-confined anode target. The researchers designed and fabricated nanowire-shaped anodes that confine the interaction volume between electron-beams and anodes, creating an X-ray “source size” that is determined by the dimension of the nanoscale anode, resulting in enhanced spatial resolution of 3D images. Combined with a self-developed image correlation algorithm and a state-of-the-art scientific CMOS camera, the improved X-ray tomography system can analyze samples in size ranging from 30-1000 micrometers, with the imaging resolution enhanced from typical 400-700 nanometers to 100-200 nanometers. The image acquisition time has also been reduced by at least 5-10 times compared to the previous conventional SEM system.

The paper’s lead author Luis Gomes Perini said the improved system paves the way to fast, non-destructive 3D imaging of materials with deca-nanometer resolution, which could be used in the development of innovative materials and for inspection and failure analysis of materials, devices and fabrication processes such as additive manufacturing.

Source: “Developments on a SEM-based X-ray tomography system: Stabilization scheme and performance evaluation,” by L. A. Gomes Perini, P. Bleuet, J. Filevich, W. Parker, B. Buijsse, and L. F. Tz. Kwakman, Review of Scientific Instruments (2017). The article can be accessed at https://doi.org/10.1063/1.4989406 .